Process of producing decorative fiberboard



Patented Aug. 13, 1940 UNITED STATES PROCESS OF rnonucme DECORATIVE 4 rmnanona Fergus A. Irvine, New Orleans, La., assignor, by mesne assignments, to The Oelotex corpora-- tion, a corporation of Delaware No Drawing. Application September 25, 1934, Serial No. 745,448

2 Claims.

This invention relates to new processes of manufacture of board from'fiber material whereby in a simple and inexpensive manner a surface of the formed fiber material is given a decorative effect.

The object of the invention is primarily that of forming on or at the surface of a fibrous material a layer or film which is decorative yet one which it is simple to provide, may be applied cheaply and yet in the regular course of manufacture.

The invention, it is to be noted, is particularly applicable to fiber materials composed entirely or largely of cellulosic substances.

As an example of the utilization of the invention, it will be described in connection with the manufacture of what is ordinarily referred to as fiber insulation board.

In the manufacture of fiber insulation board the fiber, properly refined is felted on a board machine then squeezed in an appropriate man-- ner, to rid the fiber sheet of .surplus water,

and then the sheet passes to some form of dryer for the removal of substantially all the moisture therefrom. 5 The invention hereof is applied at some appropriate .point between the formation of the fiber sheet and the point at which the sheet is substantially dry, and for the purposes hereof, the preferred point of application selected is one just after the sheet leaves the press rolls which are employed to remove normally expressible water from the sheet, such rolls being usuallypositioned to act on the board just after it comes from the board forming machine.

Briefly, the invention involves the application of a chemical .to the wet sheet which chemical reacts during drying of the sheet to produce a surface decorative effect.

As a specific example of the invention, a dilute solution of ammonium sulphate is sprayed on the surface of the board just after it passes the press rolls. The ammonium. sulphate solution used is very dilute, about a 1% solution and only sumcient is applied 'to moisten the fibers on the surface. After the application of the ammonium sulphate, the board passes into the dryer where it is subjected to a temperature of usually about 350 F. to 500 F. and at such temperature part of the ammonia present in the chemical compound is volatilized. The acid of the compound, set free upon volatilization of the ammonia, at the elevated temperature of drying reacts with the surface fiber in effect to produce what may be termed a chemical burn and as a result the surfaces of the fibers to which the chemical was applied are changed in color.

In the specific example the color is changed to a dark brown or black and, particularly if the chemical was applied sparingly so that the board 50 surface was not completely and uniformly covered, a very pleasing contrast between the original color and the color resulting from the treatment is obtained.

In the place of the use of ammonium sulphate there may be used, as will be understood, nearly any of the ammonium salts such as ammonium phosphate, chloride, bromide, etc., or salts having an acid reaction such as paper makers alum, zinc chloride, ferric sulphate, etc.; or more difiicult to control but also usable are the acids such as sulphuric, hydrochloric, acetic, etc. The limitation of the above statements must be kept in mind, that is, the effective pH is about pH 3.5. If the concentration is too high of an acid or acid forming salt the surface fiber is completely carbonized, an undesirable effect.

On the other hand, various chemicals which form colored compounds when exposed to heat may be employed. Potassium permanganate sprayed on the wet board will on passage through the dryer produce a brown coloration; or various of the chromates will produce the characteristic coloring of the respective chromium-compounds formed.

What I claim is:

1. The process of producing a decorativesurface on felted fiberboard composed of fibers largely of cellulose content, comprising the steps of: forming a wet felted board; subjecting the wet felted board to pressing and removal of a part of the moisture therefrom; applying to a. surface thereof a dilute solution of a salt of a volatile base in combination with an acid componznt; and finally subjecting the wet treated board to an elevated temperature, about 350 F. to 500 F., thereby volatilizing the base, drying the board, and producing a pleasing decorative surface of a darkened and mottled effect on a surface of the fiber insulation board.

2. The method of subjecting a surface of a fiberboard composed'largely of cellulose containing fibers to pyrolysis, :comprising as steps: applying to a surface of a wet felted fiberboard a' dilute chemical solution causing, in the carrying out of the method by the subsequent steps thereof, the fibers at the surface of the board to be subjected to a pH of about 3.5 or lower, the application of such dilute chemical solution being non-uniform over the surface; and then subjecting the wet board, after the application of the dilute chemical solution to a surface, to drying to a surface thereof, by the action of pyrolysis resuiting therefrom, causing a decorative surfacing to be produced on the finished, dried product.

means a avmn. 

